The incidence of various neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD) and senile dementia increases with age. While PD is characterized by tremors, rigidity and bradykinesia, AD is characterized by short term memory loss followed by cognitive (intellectual) impairment affecting higher cognitive functions such as domains of language, skilled movements and recognition causing aphasia, apraxia and agnosia respectively. It also affects functions such as decision-making and planning closely related to the frontal and temporal lobes of the brain.
Epidemiology of Alzheimer's disease indicates that more than 26 million people worldwide were affected with Alzheimer's disease in 2006 and the number will increase to more than 106 million by 2050 (Brookmeyer R, Johnson E, Ziegler-Graham K, Arrighi H M, “Forecasting the Global Burden of Alzheimer's Disease. Alzheimer's and Dementia,” 3:186-191(2007). The greatest increase in prevalence of AD will occur in Asia, where 48 percent of the world's Alzheimer's cases currently reside. The number of cases is expected to grow in Asia from 12.65 million in 2006 to 62.85 million in 2050.
Alzheimer's disease is a progressive and irreversible neurodegenerative disorder, and currently no cure is available since the etiopathogenesis of this disorder is poorly understood. The marketed drugs available for AD do not prevent or reverse this disease and are approved only for the management of the symptoms (Melnikova, 2007). Early detection and therapeutic interventions are urgently needed to minimize the ill effects of this devastating disease. Traditional systems of medicine such as Ayurveda offer an extensive resource, which can be utilized for development of therapeutic intervention strategies for treatment of these disorders.
Currently plant species are extensively used for medicinal purposes. Herbs are natural and safer than synthetic drugs and they are effective in treating many complex disorders of the nervous system. For instance, Ginkgo biloba extract has been shown to block impairment in spatial learning and memory in a mouse model of AD (Quinn et. al. 2003). Similarly, past studies have shown that ashwagandha can help boost memory.
Withania somnifera (Ashwagandha) traditionally also known as Indian ginseng is one of the major herbal components of geriatric tonics mentioned in Indian systems of medicine. Ashwagandha is known for treatment and prevention of a diverse range of ailments. The traditional uses of the herb are as a tonic and invigorator. It is believed to prolong longevity, boost mental and physical stamina, and improve sexual function (which is how it earned the nickname herbal viagra). It also helps to improve learning ability and memory capacity.
Withanolide-A, one of the component of the plant extract had been shown to regenerate neurites and reconstruct synapses in severely damaged neurons in vitro (Kuboyama T, Tohda C, Komatsu K, “Neuritic regeneration and synaptic reconstruction induced by withanolide A,” Br J Pharmacol. 2005 April; 144(7):961-71).
Ghoshal (U.S. Pat. No. 6,713,092, 2004) discloses a process of preparation of Withania somnifera extract from root and leaves of 1-2 years old plant. The process comprises aqueous-alcoholic extraction in the presence of exogenous polysaccharides.
Ghoshal (U.S. Pat. No. 7,318,938, 2008) discloses Withania somnifera extract composition in the form of a stable herbaceous powder which provides enhanced cognition enhancing effects for the user. The composition comprises 8-25% of withanolide glycosides and sitoindosides, 25-75% oiligosaccharides, polysaccharide (less than 10%) and free withaferrin A (less than 2%).